In a large pitcher, juice all the lemons, taking care to not drop the seeds in.

In a blender, combine the blueberries with a bit of the basil and about ¼ cup of water, and blend until smooth.

Pour the blueberry mixture into the lemon juice, and add in the Splenda. Fill up the rest of the pitcher with water, and garnish with extra basil and fresh lemon slices. Taste the lemonade, and add more sweetener if necessary.

Refrigerate until ready to drink!